Do not execute background runner if device is suspended (#3608)

frontend/util.lua

@@ -597,4 +597,11 @@ function util.shell_escape(args)
     return table.concat(escaped_args, " ")
 end
 
+--- Clear all the elements from a table without reassignment.
+--- @table t the table to be cleared
+function util.clearTable(t)
+    local c = #t
+    for i = 0, c do t[i] = nil end
+end
+
 return util

plugins/backgroundrunner.koplugin/main.lua

@@ -66,6 +66,7 @@ local logger = require("logger")
 
 local BackgroundRunner = {
     jobs = PluginShare.backgroundJobs,
+    running = false,
 }
 
 --- Copies required fields from |job|.
@@ -160,6 +161,7 @@ function BackgroundRunner:_execute()
         local round = 0
         while #self.jobs > 0 do
             local job = table.remove(self.jobs, 1)
+            logger.dbg("BackgroundRunner: run job ", job, " @ ", os.time())
             if job.insert_sec == nil then
                 -- Jobs are first inserted to jobs table from external users. So
                 -- they may not have insert_sec field.
@@ -206,14 +208,24 @@ function BackgroundRunner:_execute()
         end
     end
 
+    self.running = false
     if PluginShare.stopBackgroundRunner == nil then
         self:_schedule()
+    else
+        logger.dbg("BackgroundRunnerWidget: stop running @ ", os.time())
     end
 end
 
 function BackgroundRunner:_schedule()
     assert(self ~= nil)
-    UIManager:scheduleIn(2, function() self:_execute() end)
+    if self.running == false then
+        logger.dbg("BackgroundRunnerWidget: start running @ ", os.time())
+        self.running = true
+        UIManager:scheduleIn(2, function() self:_execute() end)
+    else
+        logger.dbg("BackgroundRunnerWidget: a schedule is pending @ ",
+                   os.time())
+    end
 end
 
 function BackgroundRunner:_insert(job)
@@ -229,4 +241,15 @@ local BackgroundRunnerWidget = WidgetContainer:new{
     runner = BackgroundRunner,
 }
 
+function BackgroundRunnerWidget:onSuspend()
+    logger.dbg("BackgroundRunnerWidget:onSuspend() @ ", os.time())
+    PluginShare.stopBackgroundRunner = true
+end
+
+function BackgroundRunnerWidget:onResume()
+    logger.dbg("BackgroundRunnerWidget:onResume() @ ", os.time())
+    PluginShare.stopBackgroundRunner = nil
+    BackgroundRunner:_schedule()
+end
+
 return BackgroundRunnerWidget

spec/unit/background_runner_spec.lua

@@ -21,6 +21,10 @@ describe("BackgroundRunner widget tests", function()
         stopBackgroundRunner()
     end)
 
+    before_each(function()
+        require("util").clearTable(PluginShare.backgroundJobs)
+    end)
+
     it("should start job", function()
         local executed = false
         table.insert(PluginShare.backgroundJobs, {
@@ -288,4 +292,65 @@ describe("BackgroundRunner widget tests", function()
         UIManager:handleInput()
         assert.are.equal(2, executed)
     end)
+
+    it("should stop executing when suspending", function()
+        local executed = 0
+        local job = {
+            when = 1,
+            repeated = true,
+            executable = function()
+                executed = executed + 1
+            end,
+        }
+        table.insert(PluginShare.backgroundJobs, job)
+
+        MockTime:increase(2)
+        UIManager:handleInput()
+        MockTime:increase(2)
+        UIManager:handleInput()
+        assert.are.equal(1, executed)
+        -- Simulate a suspend event.
+        requireBackgroundRunner():onSuspend()
+        for i = 1, 10 do
+            MockTime:increase(2)
+            UIManager:handleInput()
+            assert.are.equal(2, executed)
+        end
+        -- Simulate a resume event.
+        requireBackgroundRunner():onResume()
+        MockTime:increase(2)
+        UIManager:handleInput()
+        assert.are.equal(3, executed)
+        MockTime:increase(2)
+        UIManager:handleInput()
+        assert.are.equal(4, executed)
+    end)
+
+    it("should not start multiple times after multiple onResume", function()
+        local executed = 0
+        local job = {
+            when = 1,
+            repeated = true,
+            executable = function()
+                executed = executed + 1
+            end,
+        }
+        table.insert(PluginShare.backgroundJobs, job)
+
+        for i = 1, 10 do
+            requireBackgroundRunner():onResume()
+        end
+
+        MockTime:increase(2)
+        UIManager:handleInput()
+        MockTime:increase(2)
+        UIManager:handleInput()
+        assert.are.equal(1, executed)
+        MockTime:increase(2)
+        UIManager:handleInput()
+        assert.are.equal(2, executed)
+        MockTime:increase(2)
+        UIManager:handleInput()
+        assert.are.equal(3, executed)
+    end)
 end)